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Your secrets are safe with quasar encryption

Intergalactic radio signals from quasars could emerge as an exotic but effective new tool for securing terrestrial communications against eavesdropping.

Japanese scientists have come up with a method for encrypting messages using the distant astronomical objects, which emit radio waves and are thought to be powered by black holes.

Ken Umeno and colleagues at the National Institute of Information and Communications Technology in Tokyo propose using the powerful radio signals emitted by quasars to lock and unlock digital communications in a secure fashion.

The researchers believe quasars could make an ideal cryptographic tool because the strength and frequency of the radio pulses they emit is impossible to predict. “Quasar-based cryptography is based on a physical fact that such a space signal is random and has a very broad frequency spectrum,” Umeno told New Scientist.

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One-time pad

Randomness provides a simple means of high-security information encryption, providing two communicating parties have access to the same source of random information. For example, a randomly generated “one-time pad” shared by two parties can be used to encrypt and decrypt a message by simply transposing each individual bit of a message for bits on the pad.

Genuine randomness is hard to generate artificially and the “pseudo-randomness” that most computers use is unsuitable for use in cryptography as patterns will be revealed over time. In addition, it is also tricky for two parties to share a source of randomness securely.

Umeno and his colleagues suggest using an agreed quasar radio signal to add randomness to a stream cipher – a method of encrypting information at high speed.

Each communicating party would only need to know which quasar to monitor and when to start in order to encrypt and decrypt a message. Without knowing the target quasar and time an eavesdropper should be unable to decrypt the message.

Internet link

Umeno believes astronomical cryptography could appeal to anyone who requires high-security communications. He adds that the method does not require a large radio antenna or that the communicating parties be located in the same hemisphere, as radio signals can be broadcast over the internet at high speed.

The researchers used quasar signals collected by Very Long Baseline Interferometry antenna at the institute to encrypt messages and have filed two patents covering quasar-based cryptography&colon; one for locking and unlocking messages and another for generating digital signatures that can be used to match messages or files to a person.

However, some cryptography researchers question the need for such an unusual means of securing messages.

“This is interesting research, but there’s no reason for anyone to use it in a practical application,” says Bruce Schneier of Counterpane Security. “Furthermore, this is a brand new idea. Why would anyone want to use something new and untested when we’ve already got lots of good cryptography?”

Markus Kuhn from the University of Cambridge, UK, adds that the physical set-up could have potential weaknesses. “It is easy to play tricks with reception antennas,” he says. For example, he suggests that an attacker could mimic a radio signal and “gain a lot of control over the signal that the receiver can see.”